Methods and compositions for spraying metal



Patented Mar. 7, 1939 UNITE-D srATEs PATENT OFFICE DIETHODS AND COMPOSITIONS FOR- SPRAYING METAL Frank Osbern Albertson and Gustav A. Olsen, Sioux City, Iowa, assignors to Albcrt'son & Company, Inc., Sioux City, Iowa, -a corporation of Iowa No Drawing. Application May 18, 1936.

p Serial No. 89,372

4 Claims. (c1. iii-40.3)

The present invention relates to methods and Sprayed metal was not satisfactorily bonded to compositions for spraying metal, and is particuthe work or to the first filling in the devices of larly concerned with such methods and composithe prior art.- tions for effecting a bonding or coating of metal Another object is the provision of an improved 5 upon other metal surfaces, such as steel or alumicold tinning compound which is equally adaptnum, able to use in tinning aluminum after the alumi- The present methods and compositions may be num has been treated with an additional supused wherever it,is desirable to secure a coating plementary wash, to render the aluminum susor a filling of metal upon a ferrous metal surface ceptible to tinning with the present compound. or an aluminum metal surface, and we do not Another object is the provision of a supplewish to be limited to the specific examples which mentary composition in the form of an aluminum at present constitute the widest application of wash which may be applied to an aluminum work the invention. piece in order to prepare it for the tinning of the By way of example, however, the invention is piece by a standard cold tinning compound of 15 being applied to the repair of automobile bodies, the type described herein. fenders, etc., for filling depressions or dents with Another object is the provision of an improved metal, which may be dressed down flush with the cold metal spraying process by means of which other surfaces of the automotive vehicle body a metal filling may be so firmly and intimately parts to present a contour which is the same as bonded to a metal work piece that the filling or that of the body before the damage to the body. coating is, for all practical purposes, an integral The present method is of particular advantage part of the work piece and it is not necessary to in this connection because the body parts are not resort to mechanical bonding devices, such as heated and there is no warping due to the heat roughening the surface, or the like. of the body parts nor any melting nor burning Another object is the provision of an improved of the sound insulating asphalt or tar coverings method of treating automotive body parts in or- 5 which are used on the inside of the modern steel der to improve the appearance of damaged parts automobile bodies. by filling in the dents or depressions, finishing,

One of the most important objects of the presand repainting such parts. ent invention is the provision of an improved Other objects and advantages will be apparent method of metal coating or filling and improved from the following description, in which various compositions for such methods by means of which examples of the application of the process and the coating or filling is so intimately bonded or the compounding of the composition are given. secured to the work piece that there is no 130551? The present methods may be carried out by bility of separation due to the vibration or stress hand, with the use of various implements of the and strain to which automotive body parts are 'most simple type, to which reference will be made 35 subjected in use. This .object is so important during the'description of the process. They are, that it may be regarded as absolutely essential however, most expeditiously carried out by the to the success of any such method or composition use of improved tools, such as sanding machines, because a filling or coating which will not stick to metal spray guns, and paint spraying devices, to

40 the automobile body part is absolutely useless and which reference will also be made. 40 a waste of time in so far as the user of the proc- For example, the complete method of preparess is concerned. ing an automotive vehicle fender or body part Another object is the provision of an improved may be carried out as follows: Assuming that the tinning composition for steel or other ferrous body of an automotive vehicle has a dent in it,

metals,ewhich is equally adapted to the tinning of which it is desirable to fill with sprayed metal, the 45 the steel -or ferrous metals and the tinning of surface of the body surrounding the dent must. sprayed metal whenever respraying is necessary, first be thoroughly cleaned. This may be done as in the case of a job where it is found that there by hand by means o1 scraping devices, sand is a low spot in the filling after the filling has paper, steel brushes, etc., but the operation is been dressed down. With the tinning compounds most quickly performed by the use of a disc of the prior art it was practically impossible to sander. Such a sander is disclosed in the prior respray metal. successfully upon a metal filling. patent of Frans O. Albertson, No. 1,954,977, is-

In such case the practice was to roughen up the sued April 17,1934, when equipped with the abrasprayed filling surface with a hack-saw, and then slve disc of U. 3. Patent No. 1,882,693 to Frans to respray on the roughened surface, but the re- 0. Albertson, et al., issued October 18, 1932. 55

In order to. enable the operator to secure a feather edge on the filling, the surface of the work piece should be sanded clean over an area extending about one inch around the proposed metal fill. All hammering and bumping out of the area of the .work piece should be done before applying the metal. No acid nor paint remover should be applied to themetal work piece.

After the surface has been cleaned satisfactorily, it should be tinned with a cold tinning compound adapted to prepare the surface for the application of the metal. A satisfactory tinning compound is very important to the success of the process, and so far as we are aware noneof the tinning compounds of the prior art are capable of producing satisfactory results. A suitable cold tinning compound for steel may be compounded as follows: The compound may bedivided into elements which require renewal from time to time and other elements which form the basis of the compound and which do not require renewal.

The latter elements of the compound which do not require renewal are listed as follows, and may be compounded in the following proportions:

Base

. Ounces Metallic mercury 56 1 Bichloride of mercury 12 Wausau quartz, sand paper grade 23 Crystolon abrasive 100 grit s 3 The elements of the cold tinning compound for steel which need to be renewed from time to time may be embodied in a solution which we prefer to call the Reviver. The reviver may consist of the following elements in the proportions stated:

' Reviver Hydrochloric acid c. c 126 Zinc chloride solution U. S. P c. c 626 Distilled water c.c 2750 Copper sulphate ounces 38 On account of the varying hardness and condition of different materials, we recommend, in tinning a surface, that an application of the reviver be rubbed on the clean surface which has been previously sanded, first. This "reviver can be applied with a rag, and the surface should be covered thoroughly and rubbed hard until it shows a clear copper finish. Then the base of the tinning compound can be applied as described herein. Another method of using the compound "base and reviver comprises the mixing of these elements separately in the proportion stated and then mixing the reviver and the base together as needed.

The cold tinning compound for steel may be made by adding 24 cubic centimeters of reviver solution to 4% ounces of the steel tinning compound base, which makes one small jar of the cold tinning compound for steel. The free mercury tends to combine with the'copper, and therefore the base and reviver should be kept separate and mixed as used, or preferably applied separately as described above.

In order that the operation of the cold tinning compound on the metal work piece may be understood, we shall describe in greater detail one theory of its operation. The cold tinning compound for steel includes the quartz and Crystolon abrasive for the purpose of aiding in the cleaning of the work surface through the abrasive action of these materials, and in order to give the compound a suitable body. The Crystolon abrasive is primarily for the purpose of abrasion, while the quartz is primarily for the purpose of giving body to the compound.

Steel can be plated with copper by application of a copper sulphate solution to a properly cleaned steel surface, and this is the purpose of the use of copper sulphate in the composition. The hydrochloric acid and zinc chloride are believed to act as a flux or a cleanser in removing the oxide film from the metal, assisted by the abrasive, which exposes new metal surface to the action of the composition.

The bichlorlde of mercury goes into solution, and is adapted to combine with the copper, which becomes applied to the steel surface to form an amalgam of 'mercury, which is further adapted to combine with the free metallic mercury in the compound to provide a more substantial coating of mercury over the copper plating. The copper adheres to the steel or other ferrous surfaces, and the mercury combines with and adheres to the copper, forming a tinned surface, which also includes zinc of the zinc chloride solution. This tinned surface has the appearance of bright tin,

and is adapted to effect an intimate and secure bond between the sprayed metal and the ferrous metal work piece.

The cold tinning compound for steel should be applied as follows: A wooden paddle is provided for mixing the compound thoroughly and for applying it to the metalsurface. The compound is applied to all parts of the surface with the wodden paddle. A thick felt pad or applicator with-a metal handle is provided for the purpose of rubbing the compound into the surface of the metal. The felt base applicator should be thoroughly soaked with distilled water so that the liquid ingredients of the compound will not be lost by soaking into the felt. The applicator may then be .wet with the reviver", which is first applied and afterward used to apply the base of the compound, and the surface should be thoroughly rubbed until it presents the appearance of a brightly tinned surface. Theexcesscompound should then be wiped oil, with, a clean dry cloth, which also brings out the bright finish. If the surface is not uniformly tinned, as indicated by its uniform bright appearance, more compound should be applied with the wooden paddle and rubbedin with the felt applicator.

It should be noted that the foregoing cold tinning compound for steelshould not be applied directly to aluminum, but further instructions for its use on aluminum will be given hereinafter in this description. v

The step of spraying the metal on the prepared tinned surface comes next in the application of a metal coating or filler. This step is preferably carried out by means of a metal spray gun of the type covered by the patent of Albertson & Co., Inc., No. 2,058,653, issued Oct. 27, 1936, but the spraying may also be carried on by hand with the Air is supplied by means of an air nozzle, pref- I erably of the shape shown in said patent nozzles should preferably be held preferably in the form of sticks,

metal well of the gun, as dethe work piece so, that it may minute at '10 pounds.

tions are filled and covered brace the end of the metal nozzle,

nozzle is properly positioned with respect to the. metal nozzle. The spraying is brought about by air on the metal emerging from the-action of the the metal nozzle ofjthe metal well, and the two quite close to inches the work at a distance of from one to two from the work piece.

The metal to be sprayed upon the prepared tinned surface may be any standard solder metal, that the stick can be fed into the sired. The amount of metal is controlled by the hand feeding of the stick, more metal being melted and supplied when a greater pressure is applied to the stick.

It is important that the metal alloy be pure and clean in order to make sure that it will adhere firmly to the prepared surface.

With a gun of the type described in said patent,

air pressure at from to 90 poundsis used. the gun requiring about seven cubic feet per and the water should be drained from the air line. The metal well in the gun should becarefully cleaned before and after spray g, and a blow-out tool that is provided with the gun should be used to deflect the air up into the well to'clean out the metal nozzle.

A fine evenly be sprayed upon the prepared operator should first spray a thin layer of metal, covering the entire tinned surface. The nozzle should be moved in a circular motion around the outer edge and toward the center with a uniform control of the air and uniform feeding of the metal. I 4

Should a blotch of molten metal be blownupon the job, it should be removed and the spray evenly applied. When more than one place isto distributed spray of metal should 'be repaired, each place should be tinned'and at a tim Any spray dust appearsanded surface, after timing one be removed before that place is tinned, preparatory to its being sprayed. The spray should be continued and applied uniformly until the metal sprayed one with sprayed metal above the normal surface of the work piece. Thus, an excess of metal should bes'prayed upon besanded-down to the desired finish and level in order to provide a smooth surface for the application of the paint.

The sprayed metal filling should then be sanded down, preferably with a disc sander of the type referred to above, and the sanding should be, continued until the edges of the filling -are dressed down to a smooth-feather edge and until all parts of the filling are flush with the surface of the work pieces, or shaped as desired.

. In case it-is found, after sanding the sprayed metal, that the surface has not been built up sufficlently above the desired finishing level, so that it is necessary to spray more metal on the filling,

end of the gun melts,

'Ihe.air should be dry,

surface, and the is built up and until-all indentabe sanded smooth preof the tinning then the surface should liminary to the second application compound.

The tinnlng compound for steel as described above purposely includes an excess of metallic mercury over that required for effective tinning on steel or other ferrous metals. Approximately one-eighth as much metallic for the purpose of tinning steel surfaces in the compound, but we have discovered that the same compound may be used for 'tinning a surface to be resprayed by using an excess of metallic mercury as descri The smooth filler surface is then tinned with the same compound, which is applied in the same manner, with a. wooden paddle, and rubbed in with a felt applicator. In this case it-is necessary to rub thoroughly with considerable pressure, and the filler surface will appear dark until the rubbing has effected atinning of the surface. Three or more applications of the tinning compound should be made and thoroughly rubbed in, in the case of respraying. The rubbing should be continued until-all the black spots have disap peared. The surface should then be sprayed at once, before the mercury in the compound hardens. I It is found that in the original spraying of the metal On a prepared tinned steel surface it is not necessary to spray at once, as the tinned surface will still be effective for some time after it has been'tinned. I

In the case of a respraying operation, how- ,ever, it is important that the respraying be done immediately after the double application of the tinning compound, as the mercury seems to be absorbed from the surface by the filler metal and the tinned surface is effective only if sprayed immediately.

It will thus be tinning compound which is used for steel according to the present invention may also be used for tinning a sprayed metal surface for a respraying operation. This was not possible with any of the compounds as we are aware has never before bythe use of any compound.

In the case ofan application of sprayed metal to aluminum, it is important that the mercury of the compou d does not come in contact with any aluminum. Metallic mercury tends to combine chemically with aluminum and causes it to bloom; that is, the metallic mercury attacks the aluminum and forms a chemicalcompound on the surface of the aluminum. which builds up rapidly. Therefore, it is evident that any tinning of the prior art, and so far been accomplished mercury, or seven .ounces of metallic mercury, would be sufficient 1 observed that the same cold compound which. includes metallic mercury cannotbe successfully used if the metallic mercury comes in direct contact with the. aluminum,

as it would if the cold tinning compound for steel Silver nitrate Concentrated nitric acidc.c. 2 Distilled water' c.c. ,38

The elements of the aluminum wash are thoroughly mixed together, and the wash may be applied to the aluminum surface, which has first been cleaned .with-a sanding disc, as described with respect to steel. Then a sufficient area outside of the sanded surface to be tinned should be covered to protect the aluminum from the cold tinning compound, which is injuriousto the bare aluminum surface. A brush is furnished with a bottle of the aluminum wash, and it may be applied in the same manner as paint is applied.

. The mercury present in the cold tinning comis applied in the usual manner, and the steps in the spraying of metal on aluminum are the same pound is injurious to aluminum, and it is very important that the compound be kept away from the. unprotected aluminum surface.

Furthermore, we recommend that any materials such as compound paddle, rags, and even a container or any water that has been used with aluminum wash be used only on aluminum and kept away from the base compound, as the smallest particle of aluminum wash mixed with the base compound will be detrimental to the application of the base" tinning compound on steel. The action of the aluminum wash is as follows:

Aluminum may be plated with "silver, and the silver nitrate applied to the cleaned al num surface acts to combine with the'aluminum to form a layer of silver on the aluminum. The silver layer positively protects the aluminum from the direct action of metallic mercury. The nitric acid tends to clean the aluminum surface for application of the silver. 'The cold tinning compound for steel may then also be used for aluminum after the aluminum-has been protected with the aluminum wash. The tinning compound as those described with respect to steel, from this point.

Before painting a surface which has been treated with aluminum wash, the surface should be washed, including the feather edges and every part to which wash 01' compound has been applied, with a caustic soda solution, to effect a thorough cleaning. L

It will thus be observed that by means of an aluminum wash or a composition forthe protection of the aluminum surface from' the metallic mercury the same cold tinning compound which is applicable to steel and other ferrous metals may be used upon aluminum. This is a great advantage, as it is necessary for the operator to buy only one type of tinning compound, and it is necessary for the inventor to stock only one type of tinning compound; which is of universal application. Needless to say, the tinning compound may also be used upon other metals, such as copper, iron, etc. 4

After the sprayed metal surface has been satisfactorily smoothed to the contour desired, the work piece, such as an automotive body, may then be refinished with paint in the usual manner, preferably by spraying.

The metal used for spraying is preferably the ordinary 30 to '70 per cent soldermixture, which may be purchased on the open market in various forms.

It will thus be observed that we have invented an improved tinning compound which is adaptable. to universal use upon prepared steel surfaces and for respraying a sprayed metal surface. Our compound may also be used for tinning aluminum surfaces by means of the preliminary use of an aluminum wash adapted to coat the aluminum with a metal which will plate aluminum so that the aluminum is protected from the metallic mercury in the tinning compound.

The metal sprayed on the prepared metal suris applied to the inside of such steel bodies melted 10 l or damaged by the low degree of heat applied. Modern automotive bodies now have such a compound applied to the interior of the body for the purpose of deadening sound, and the present spraying methods may be used without any dam- 5 age to thesound deadening qualities of the liningon themetal body.

Perhaps one of the most important features of the present method and compositions is that the sprayed metal adheres so tightly to the prepared 20 surfaces that there is no danger of the filling or coating ever coming off when subjected to the stress and strain and vibration whichv are incident to the use of the automotive vehicle.

While we have illustrated a preferred embodiment of our invention, many modifications may be made without departing from the spirit of the invention, andwedo not wish to be limited to the precise details of construction set forth, but desire to avail ourselves of all changes within the scope of the appended claims.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States, is:

1. The method of repairing metal bodies comprising exposing a clean metal surface by abrasion of the body, applying a tinning compound comprising hydrochloric acid, bichloride of mercury, and an excess of metallic mercury, rubbing the cleaned metal surface with said compound 40 until a uniform bright tinned surface'is produced, and applying metal to said surface in the form of a meltable solder composition,- melted and reduced to a finely divided spray and directed against the tinned-surface by compressed air. 5

2. The method of repairing metalbodies comprising exposing a clean metal surface by abrasion of the body, applying a tinning compound comprising an abrasive, hydrochloric acid, bi-

chloride of mercury, and an excess of metallic 5o mercury, rubbing the cleaned metal surface with said compound until a uniform bright tinned surface is produced, and applying metal to said surface in the form of a meltable solder composition,

'melted and reduced to a finely divided spray and 66 directed against the tinned surface by compressed air, the sprayed metal being applied thinly and evenly'with a rotary motion until a predeterminedlevel of metal has been built up. w

3. The method of repairing metal bodies comprising exposing a clean metal surface by abrasion of the body, applying a tinning compound comprising an abrasive, hydrochloric acid, bi-' chloride of mercury, and an excess of metallic a mercury, rubbing the cleaned metal surface with said compound until a uniform bright tinnedsurface is produced, and applying metal to said surface in the form of a meltable solder composition, melted and reduced to a finely divided 7o spray and directed against the tinned surface by compressed air, the sprayed metal being applied thinly and evenly with a rotary motion until a predetermined level of metal has been built up,

and sanding the sprayed metal filling until the 1 edges thereof are dressed down to a smooth feather edge.

, 4. A cold tinning compound for ferrous metals, comprising a base having an excess of metallic mercury, bichloride of mercury, quartz particles, and abrasive, with a. solution comprising hydrochloric acid, zinc chloride, distilled water,. and

copper sulphate, the baseand s lution being mixed separately and assembled immediately prior to their application to the ferrous metal, whereby the ferrous metal is adapted to be provided with a tightly adhering coating of tree mercury.

FRANK OSBERN ALBERTSON.

CGUSTAV A. OLSEN. 

